1. Field of the Invention
The present invention relates to cups and more particularly to disposable cups intended for containing hot beverages, such as coffee, tea and soup.
2. Description of the Related Art
In this day of fast food restaurants, disposable beverage cups are commonly used. A simple paper cup can be used when the beverage is cold. However when the beverage is hot and contains such things as coffee, tea, soup or the like, the heat from the heated liquid can readily penetrate through the sidewall of the beverage cup making it literally impossible for the consumer to hold the beverage cup with a bare hand.
In the past, it has been known to make beverage cups from an expanded resin material which is sold under the trademark styrofoam. Such cups are excellent thermal insulators and not only can be used to prevent the burning of a consumer's hand when utilizing of hot beverages but also for cold beverages. Such cups will tend to maintain the beverage colder for a longer period of time. Such cups are comfortable to use as the exterior surface of the cup stays close to ambient temperature regardless of the temperature of the ingredients within the cup. However, such cups are environmentally unfriendly because they are not biodegradable or recyclable. If such a cup is merely discarded into the environment by a careless or uncaring individual, the cup does not deteriorate and will remain creating a blighted appearance in the environment. Such cups, when discarded in landfills, will remain intact for literally thousands of years since deterioration does not occur.
A more environmentally acceptable beverage cup is one composed of paper which is biodegradable and in which the principal constituent is cellulose or vegetable fiber. The container surface of the cup is rendered liquid-proof by coating of the surface with a thin coating of a paraffin or microcrystalline wax for a cold beverage or with a thin coating of a synthetic high polymer having a high melting point, such as polypropylene or polyethylene for hot beverages. However, heat exchange from the container of the beverage cup through the sidewall of the beverage cup is rapid and if it is an especially hot liquid, such as coffee, tea or soup, that liquid can easily burn the consumer's hand.
In the past, it has been known to construct the sidewall of a paper cup in a manner to insulate the consumer's hand from the heat of the liquid contained within the beverage cup. It has been known to coat the exterior sidewall of the beverage cup with a foam coating which insulates from the transfer of heat. It has also been known to construct a sidewall of the beverage cup of a corrugated paper which has a lot of open air cells which again function to insulate the consumer's hand from the heat contained within liquid in the beverage cup. However in the past, some constructions have proved to be quite expensive as if a manufacturer is to enjoy widespread marketing of such a cup, it has to be manufactured at a very inexpensive price. A very inexpensive price is around a penny per cup. There is a need to construct a paper cup to thermally insulate the consumer's hand and having this paper cup to be manufactured most inexpensively.